(I’m mainly talking comics here)
I like crossovers. I’ve even got plans for a crossover involving characters from some of my books, although that’s a fair way off.
I also (in theory) enjoy crossovers in comics, although many recent ones have been disappointing. I’m not talking about the small crossovers, where a character appears in another characters’ comic, but the Crossover EVENT comics.
I find them more successful where they’re relatively contained, such as some of the X-Men Events of recent years (Messiah Complex, Utopia, X-Nation, Second Coming) where the story runs between regular issues of the comics.
Where I find them less successful is when there’s a mini-series, with regular series having side-stories which are allegedly not needed to enjoy the main story (examples include Secret Invasion, Siege, Fear Itself). Even those I enjoy feel a bit rushed in the mini-series, since they need to allow space for the associated series to fill out the story. It feels like you’re only getting the bare bones of the story, which can affect the pacing.
Sometimes it can’t really be helped. Overall I liked the idea of Secret Invasion, and the flashbacks in other series showing how the plot occurred behind the scenes for the past few years worked for me. But they would have slowed the main series down too much. Could it still have worked with a meatier story in the main mini-series? I think so. The background stuff just enhanced the overall story.
A subcategory of events is the alternate world stuff (Age of Apocolypse, House of M, Flashpoint, Age of X). While I enjoy some alternate world stories, Events often leave me cold. No matter how much they supposedly affect the regular continuity, they never really feel like they matter that much. (And since Flashpoint was simply a story rationale for rebooting the DC Universe, which included CANCELLING SECRET SIX, it in my view wallows at the nadir of such events.)
Okay, most Events are there mainly to serve a marketing purpose, trying to get readers of one comic hooked on others. So should they get judged on different criteria? Not really. They don’t usually get priced any cheaper, and the fact that some Events are enjoyable means that there’s nothing inherently bad about the type of story.
They usually seem to fall apart when there’re a number of creators working on parts of the main story, and lack of communication and organization cause problems. Final Crisis on its own felt fairly self-contained if memory serves, as long as you ignored the events in some of the lead up titles which contradicted elements of the set-up (but since I didn’t read all of those I found the main series relatively enjoyable).
The main thrill of a crossover is characters crossing over into each other’s stories, though, and having them interact. Which isn’t to say that should be the focus, since a weak story just to allow two characters to interact will leave the encounter unsatisfactory. Ideally the story should have a reason for all the characters to be involved, and all should have something to do other than just interacting.
With a firm control over the story, though, and using only characters who have valid reasons to be involved, crossovers can be fun, and I really want to do one.